Managing tissue treatment

ABSTRACT

Various embodiments are directed to systems and methods for providing segmented power curves to tissue. A surgical generator may receive an indication of a first impedance of tissue to be treated by a surgical end effector. The generator may determine that the first impedance is within an impedance range corresponding to a first power curve segment of the segmented power curve and provide a drive signal to the end effector according to a first power curve. The generator may further receive an indication of a second impedance of the tissue to be treated by the end effector, determine that the second impedance is within an impedance range corresponding to a second power curve segment of the segmented power curve, and provide the drive signal to the end effector according to a second power curve.

RELATED APPLICATION

This application is related to concurrently filed U.S. application Ser.No. 14/660,627, entitled “Managing Tissue Treatment”, now U.S. PatentApplication Publication No. 2016/0270841, which is incorporated hereinby reference in its entirety.

BACKGROUND

Various embodiments are directed to surgical systems that may beutilized in electrosurgical and/or ultrasonic devices to manage thedelivery of energy to tissue to optimize tissue treatment.

Electrosurgical devices for applying electrical energy to tissue inorder to treat and/or destroy the tissue are commonly used in surgicalprocedures. An electrosurgical device may comprise a handle and aninstrument having a distally-mounted end effector (e.g., one or moreelectrodes). The end effector can be positioned against the tissue suchthat electrical current is introduced into the tissue. Electrosurgicaldevices can be configured for bipolar or monopolar operation. Duringbipolar operation, current is introduced into and returned from thetissue by active and return electrodes, respectively, of the endeffector. During monopolar operation, current is introduced into thetissue by an active electrode of the end effector and returned through areturn electrode (e.g., a grounding pad) separately located on apatient's body. Heat generated by the current flow through the tissuemay form hemostatic seals within the tissue and/or between tissues andthus may be particularly useful for sealing blood vessels, for example.The end effector of an electrosurgical device may also comprise acutting member that is movable relative to the tissue and the electrodesto transect the tissue.

Electrical energy applied by an electrosurgical device can betransmitted to the instrument by a generator in communication with thehandle. The electrical energy may be in the form of radio frequency(“RF”) energy. RF energy is a form of electrical energy that may be inthe frequency range of 300 kHz to 1 MHz. During its operation, anelectrosurgical device can transmit low frequency RF energy throughtissue, which causes ionic agitation, or friction, in effect resistiveheating, thereby increasing the temperature of the tissue. Because asharp boundary may be created between the affected tissue and thesurrounding tissue, surgeons can operate with a high level of precisionand control, without sacrificing un-targeted adjacent tissue. The lowoperating temperatures of RF energy may be useful for removing,shrinking, or sculpting soft tissue while simultaneously sealing bloodvessels. RF energy may work particularly well on connective tissue,which is primarily comprised of collagen and shrinks when contacted byheat.

Ultrasonic surgical devices, such as ultrasonic scalpels, are anothertype of powered surgical devices used in surgical procedures. Dependingupon specific device configurations and operational parameters,ultrasonic surgical devices can provide substantially simultaneoustransection of tissue and homeostasis by coagulation, desirablyminimizing patient trauma. An ultrasonic surgical device may comprise ahandle containing an ultrasonic transducer, and an instrument coupled tothe ultrasonic transducer having a distally-mounted end effector (e.g.,a blade tip) to cut and seal tissue. In some cases, the instrument maybe permanently affixed to the handle. In other cases, the instrument maybe detachable from the handle, as in the case of a disposable instrumentor an instrument that is interchangeable between different handles. Theend effector transmits ultrasonic energy to tissue brought into contactwith the end effector to realize cutting and sealing action. Ultrasonicsurgical devices of this nature can be configured for open surgical use,laparoscopic, or endoscopic surgical procedures includingrobotic-assisted procedures.

Ultrasonic energy cuts and coagulates tissue using frictional heatingand can be transmitted to the end effector by an ultrasonic generator incommunication with the transducer. Vibrating at high frequencies (e.g.,55,500 times per second), the ultrasonic blade denatures protein in thetissue to form a sticky coagulum. Pressure exerted on tissue by theblade surface collapses blood vessels and allows the coagulum to form ahemostatic seal. A clinician can control the cutting speed andcoagulation by the force applied to the tissue by the end effector, thetime over which the force is applied and the selected excursion level ofthe end effector.

SUMMARY

Various embodiments are directed to systems and methods for providingsegmented power curves to tissue. A surgical generator may receive anindication of a first impedance of tissue to be treated by a surgicalend effector. The generator may determine that the first impedance iswithin an impedance range corresponding to a first power curve segmentof the segmented power curve and provide a drive signal to the endeffector according to a first power curve. The generator may furtherreceive an indication of a second impedance of the tissue to be treatedby the end effector, determine that the second impedance is within animpedance range corresponding to a second power curve segment of thesegmented power curve, and provide the drive signal to the end effectoraccording to a second power curve.

In some embodiments, the generator may provide a drive signal to the endeffector according to a first power curve, determine that an impedanceof tissue treated by the end effector has moved from an impedance rangecorresponding to a first power curve segment to an impedance rangecorresponding to a second power curve segment, and provide the drivesignal to the end effector according to the second power curve.

FIGURES

The novel features of the various embodiments are set forth withparticularity in the appended claims. The described embodiments,however, both as to organization and methods of operation, may be bestunderstood by reference to the following description, taken inconjunction with the accompanying drawings in which:

FIG. 1 illustrates one embodiment of a surgical system comprising agenerator and various surgical devices usable therewith.

FIG. 2 illustrates one embodiment of an example ultrasonic device thatmay be used for transection and/or sealing.

FIG. 3 illustrates one embodiment of the end effector of the exampleultrasonic device of FIG. 2.

FIG. 4 illustrates one embodiment of a clamp arm assembly that may beemployed with the ultrasonic device of FIG. 2.

FIG. 5 is a schematic diagram of a tissue impedance module of thegenerator of FIG. 1 coupled to the blade and the clamp arm assembly ofFIGS. 3 and 4 with tissue located therebetween.

FIG. 6 illustrates one embodiment of an example electrosurgical devicethat may also be used for transection and sealing.

FIGS. 7, 8, and 9 illustrate one embodiment of the end effector shown inFIG. 6.

FIGS. 10, 11, 12, 13 and 13A illustrate one embodiment of an alternativeend effector 132′ that may be used with the electrosurgical device shownin FIG. 6.

FIG. 14 illustrates one embodiment of the surgical system of FIG. 1.

FIG. 15 shows a perspective view of one example embodiment of a surgicalsystem comprising a cordless electrical energy surgical instrument withan integral generator.

FIG. 16 shows a side-view of a handle of one embodiment of the surgicalinstrument of FIG. 9 with half of the handle body removed to illustratevarious components therein.

FIG. 17 shows one embodiment of an RF drive and control circuit.

FIG. 18 shows one embodiment of the main components of a controlcircuit.

FIG. 19 illustrates one embodiment of a chart showing example powercurves.

FIG. 20 illustrates one embodiment of a process flow for applying one ormore power curves to a tissue bite.

FIG. 21 illustrates one embodiment of a chart showing example powercurves that may be used in conjunction with the process flow of FIG. 20.

FIG. 22 illustrates one embodiment of a chart showing example commonshape power curves that may be used in conjunction with the process flowof FIG. 20.

FIGS. 23-25 illustrate process flows describing routines that may beexecuted by a digital device of the generator to generally implement theprocess flow of FIG. 20 described above.

FIG. 26 illustrates one embodiment of a process flow for applying one ormore power curves to a tissue bite.

FIG. 27 illustrates one embodiment of a segmented power curve.

FIG. 28 illustrates an alternative embodiment of a segmented powercurve.

FIG. 29 illustrates a plot showing an implementation of the segmentedpower curve of FIG. 28 according to one embodiment.

FIG. 30 illustrates a state diagram showing one embodiment of a statediagram that may be implemented by a surgical system to execute asegmented power curve.

FIG. 31 illustrates a flow chart showing one embodiment of a processflow that may be executed by a surgical system to execute a segmentedpower curve.

FIG. 32 illustrates a flow chart showing one embodiment of a processflow that may be executed by a surgical system (e.g., a generator 102,220 thereof) to execute a segmented power curve using a look-up table.

FIG. 33 illustrates a flow chart showing one embodiment of a processflow for modifying a drive signal when a previous energy cycle hasalready been applied to a tissue bite.

FIG. 34 illustrates a flow chart showing another embodiment of a processflow for modifying a drive signal when a previous energy cycle hasalready been applied to a tissue bit.

DESCRIPTION

Before explaining various embodiments of surgical devices and generatorsin detail, it should be noted that the illustrative embodiments are notlimited in application or use to the details of construction andarrangement of parts illustrated in the accompanying drawings anddescription. The illustrative embodiments may be implemented orincorporated in other embodiments, variations and modifications, and maybe practiced or carried out in various ways. Further, unless otherwiseindicated, the terms and expressions employed herein have been chosenfor the purpose of describing the illustrative embodiments for theconvenience of the reader and are not for the purpose of limitationthereof. Also, it will be appreciated that one or more of thefollowing-described embodiments, expressions of embodiments and/orexamples, can be combined with any one or more of the otherfollowing-described embodiments, expressions of embodiments and/orexamples.

In some embodiments, a surgical system may be configured to provide adrive signal to an end effector of an ultrasonic or electrosurgicalinstrument according to a segmented power curve. A segmented power curvemay be a power curve having designated impedance ranges or segments.Each segment may be associated with one or more power curves. Whentissue treated by the end effector exhibits a tissue impedance in afirst power curve segment associated with a first power curve, then thesurgical system may apply the first power curve. When the tissue treatedby the end effector exhibits a tissue impedance in a second power curvesegment associated with the second power curve, the surgical system mayapply the second power curve. The second power curve, in someembodiments, may be less aggressive than the first power curve. In someexamples, the second power curve corresponds to a constant power (e.g.,0-5 Watts). In this way, the tissue may rest or coast during applicationof the second power curve.

In some embodiments, the surgical system may be configured to modify anenergy cycle provided to tissue by an ultrasonic or electrosurgical endeffector if a clinician requests a second or subsequent energy cycle onthe same tissue bite. When an energy cycle is requested, the generatormay determine whether the end effector is positioned to treat the sametissue that was treated by the previous energy cycle. For example, whenan energy cycle is requested, the generator may be configured todetermine whether jaws of the end effector have been opened since thecompletion of the previous energy cycle (e.g., whether the jaw apertureor distance between the jaw members has increased). If the jaws have notbeen opened since the previous energy cycle, it may indicate that theend effector is positioned to treat the same tissue bite. If the endeffector is positioned to treat the same tissue bite, the generator maybe configured to modify the requested energy cycle. For example, thegenerator may apply a less aggressive power curve and/or modifyparameters of the applied power curve or curves to reduce the amount ofpower provided. In this way, the generator may reduce the risk ofdamaging tissue by overtreatment.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a clinician gripping a surgical device. Thus,an end effector is distal with respect to the more proximal portion ofthe surgical device gripped by the clinician. It will be furtherappreciated that, for convenience and clarity, spatial terms such as“top” and “bottom” may also be used herein with respect to the cliniciangripping the surgical device. However, surgical devices are used in manyorientations and positions, and these terms are not intended to belimiting and absolute.

FIG. 1 illustrates one embodiment of a surgical system 100 comprising agenerator 102 configurable for use with surgical devices. According tovarious embodiments, the generator 102 may be configurable for use withsurgical devices of different types, including, for example, theultrasonic surgical device 104 and electrosurgical or RF surgical device106. Although in the embodiment of FIG. 1 the generator 102 is shownseparate from the surgical devices 104, 106, in certain embodiments thegenerator 102 may be formed integrally with either of the surgicaldevices 104, 106 to form a unitary surgical system.

FIG. 2 illustrates one embodiment of an example ultrasonic device 104that may be used for transection and/or sealing. The device 104 maycomprise a handle 116 which may comprise an ultrasonic transducer 114.The transducer 114 may be in electrical communication with the generator102, for example, via a cable 112 (e.g., a multi-conductor cable). Thetransducer 114 may comprise piezoceramic elements, or other elements orcomponents suitable for converting the electrical energy of a drivesignal into mechanical vibrations. When activated by the generator 102,the ultrasonic transducer 114 may cause longitudinal vibration. Thevibration may be transmitted through an instrument portion 124 of thedevice 104 (e.g., via a waveguide embedded in an outer sheath) to an endeffector 126 of the instrument portion 124.

FIG. 3 illustrates one embodiment of the end effector 126 of the exampleultrasonic device 104. The end effector 126 may comprise a blade 151that may be coupled to the ultrasonic transducer 114 via the wave guide(not shown). When driven by the transducer 114, the blade 151 mayvibrate and, when brought into contact with tissue, may cut and/orcoagulate the tissue, as described herein. According to variousembodiments, and as illustrated in FIG. 3, the end effector 126 may alsocomprise a clamp arm 155 that may be configured for cooperative actionwith the blade 151 of the end effector 126. With the blade 151, theclamp arm 155 may comprise a set of jaws 140. The clamp arm 155 may bepivotally connected at a distal end of a shaft 153 of the instrumentportion 124. The clamp arm 155 may include a clamp arm tissue pad 163,which may be formed from TEFLON® or other suitable low-frictionmaterial. The pad 163 may be mounted for cooperation with the blade 151,with pivotal movement of the clamp arm 155 positioning the clamp pad 163in substantially parallel relationship to, and in contact with, theblade 151. By this construction, a tissue bite to be clamped may begrasped between the tissue pad 163 and the blade 151. In someembodiments, a strain gauge 156 or other pressure sensor may bepositioned on the clamp arm 155, for example, between the clamp pad 163and clamp arm 155, to measure the pressure exerted on tissue heldbetween the clamp arm 155 and the blade 151. Also, in some embodiments,the clamp arm 155 may comprise a temperature sensor 158 for sensing atemperature of tissue between the clamp arm 155 and the blade 151. Thetemperature sensor 158 may be, for example, a thermocouple, a resistivetemperature device, an infrared sensor, a bimetallic device, etc.

The tissue pad 163 may be provided with a sawtooth-like configurationincluding a plurality of axially spaced, proximally extending grippingteeth 161 to enhance the gripping of tissue in cooperation with theblade 151. The clamp arm 155 may transition from the open position shownin FIG. 3 to a closed position (with the clamp arm 155 in contact withor proximity to the blade 151) in any suitable manner. For example, thehandle 116 may comprise a jaw closure trigger 138. When actuated by aclinician, the jaw closure trigger 138 may pivot the clamp arm 155 inany suitable manner. For example, the jaw closure trigger 138 may becoupled to a jaw closure member 141 extending through the shaft 124 tothe clamp arm 155. Proximal motion of the jaw closure trigger 138 maycause corresponding proximal motion of the jaw closure member 141, whichmay pull the clamp arm 155 towards the blade.

The generator 102 may be activated to provide the drive signal to thetransducer 114 in any suitable manner. For example, the generator 102may comprise a foot switch 120 coupled to the generator 102 via afootswitch cable 122 (FIG. 14). A clinician may activate the transducer114, and thereby the blade 151 by depressing the foot switch 120. Inaddition, or instead of the foot switch 120 some embodiments of thedevice 104 may utilize one or more switches or buttons positioned on thehandle 116 that, when activated, may cause the generator 102 to activatethe transducer 114. In some embodiments, the handle 116 may comprise apair of buttons 136 a, 136 b positioned relative to the closure trigger138 to allow the clinician to operate the buttons 136 a, 136 b with anindex finger, for example, while gripping the closure trigger 138. Inother embodiments, the buttons 136 a, 136 b may be replaced with asingle similarly located button. Also, for example, one or moreadditional buttons, such as 136 c, may be positioned on an upper portionof the handle 116. For example, the button 136 c may be configured to,when depressed, cause the generator 102 to provide a pulsed output. Thepulses may be provided at any suitable frequency and grouping, forexample. In certain embodiments, the power level of the pulses may bethe power levels set utilizing buttons 136 a, 136 b, as described above.Also, in some embodiments, the generator 102 may be activated based onthe position of the jaw closure trigger 138, (e.g., as the cliniciandepresses the jaw closure trigger 138 to close the jaws 140, ultrasonicenergy may be applied).

The various buttons 136 a, 136 b, 136 c may be hardwired and/orprogrammable to, when depressed, bring about various effects on thedrive signal provided to the transducer 114. For example, in someembodiments, the state of the buttons 136 a, 136 b may be communicatedto the generator 102. In response to the state of the buttons, thegenerator 102 may determine an operating mode of the device 104,expressed as the form of the drive signal provided by the generator 102.When the button 136 a is depressed, for example, the ultrasonicgenerator 102 may provide a maximum drive signal to the transducer 114,causing it to produce maximum ultrasonic energy output. Depressingbutton 136 b may cause the generator 102 to provide a user-selectabledrive signal to the transducer 114, causing it to produce less than themaximum ultrasonic energy output.

It will be appreciated that the ultrasonic device 104 may comprise anycombination of the buttons 136 a, 136 b, 136 c. For example, the device104 could be configured to have only two buttons: a button 136 a forproducing maximum ultrasonic energy output and a button 136 c forproducing a pulsed output at either the maximum or less than maximumpower level per. In this way, the drive signal output configuration ofthe generator 102 could be 5 continuous signals and 5 or 4 or 3 or 2 or1 pulsed signals. In certain embodiments, the specific drive signalconfiguration may be controlled based upon, for example, EEPROM settingsin the generator 102 and/or user power level selection(s).

In certain embodiments, a two-position switch may be provided as analternative to a button 136 c. For example, a device 104 may include abutton 136 a for producing a continuous output at a maximum power leveland a two-position button 136 b. In a first detented position, button136 b may produce a continuous output at a less than maximum powerlevel, and in a second detented position the button 136 b may produce apulsed output (e.g., at either a maximum or less than maximum powerlevel, depending upon the EEPROM settings).

In some embodiments, the end effector 126 may also comprise a pair ofelectrodes 159, 157. The electrodes 159, 157 may be in communicationwith the generator 102, for example, via the cable 128. The electrodes159, 157 may be used, for example, to measure an impedance of a tissuebite present between the clamp arm 155 and the blade 151. The generator102 may provide a signal (e.g., a non-therapeutic signal) to theelectrodes 159, 157. The impedance of the tissue bite may be found, forexample, by monitoring the current, voltage, etc. of the signal. In someembodiments, the non-therapeutic signal provided to the electrodes 159,157 may be provided by the surgical device 106 itself.

FIG. 4 illustrates one embodiment of the clamp arm assembly 451 that maybe employed with the ultrasonic device 104. In the illustratedembodiment, the clamp arm assembly 451 comprises a conductive jacket 472mounted to a base 449. The conductive jacket 472 is the electricallyconductive portion of the clamp arm assembly 451 that forms the second,e.g., return, electrode. In one implementation, the clamp arm 155 (FIG.3) may form the base 449 on which the conductive jacket 472 is mounted.In various embodiments, the conductive jacket 472 may comprise a centerportion 473 and at least one downwardly-extending sidewall 474 which canextend below the bottom surface 475 of the base 449. In the illustratedembodiment, the conductive jacket 472 has two sidewalls 474 extendingdownwardly on opposite sides of the base 449. In other embodiments, thecenter portion 473 may comprise at least one aperture 476 which can beconfigured to receive a projection 477 extending from the base 449. Insuch embodiments, the projections 477 can be press-fit within theapertures 476 in order to secure the conductive jacket 472 to the base449. In other embodiments, the projections 477 can be deformed afterthey are inserted into the apertures 476. In various embodiments,fasteners can be used to secure the conductive jacket 472 to the base449.

In various embodiments, the clamp arm assembly 451 comprises anon-electrically conductive or insulating material, such as plasticand/or rubber, for example, positioned intermediate the conductivejacket 472 and the base 449. The electrically insulating material canprevent current from flowing, or shorting, between the conductive jacket472 and the base 449. In various embodiments, the base 449 may compriseat least one aperture 478, which can be configured to receive a pivotpin (not illustrated). The pivot pin can be configured to pivotablymount the base 449 to the shaft 153 (FIG. 3), for example, such that theclamp arm assembly 451 can be rotated between open and closed positionsrelative to the shaft 153. In the illustrated embodiment, the base 449includes two apertures 478 positioned on opposite sides of the base 449.In one embodiment, a pivot pin may be formed of or may comprise anon-electrically conductive or insulating material, such as plasticand/or rubber, for example, which can be configured to prevent currentfrom flowing into the shaft 153 even if the base 449 is in electricalcontact with the conductive jacket 472, for example. Additional clamparm assemblies comprising various embodiments of electrodes may beemployed. Examples of such clamp arm assemblies are described incommonly-owned and contemporaneously-filed U.S. patent application Ser.Nos. 12/503,769, 12/503,770, and 12/503,766, each of which isincorporated herein by reference in its entirety.

FIG. 5 is a schematic diagram of the tissue impedance module 402 coupledto the blade 151 and the clamp arm assembly 451 with tissue 414 locatedtherebetween. With reference now to FIGS. 1-3, the generator 102 maycomprise a tissue impedance module 402 configured for monitoring theimpedance of the tissue 414 (Z_(t)) located between the blade 151 andthe clamp arm assembly 451 during the tissue transection process. Thetissue impedance module 402 is coupled to the ultrasonic device 104 byway of the cable 112. The cable 112 includes a first “energizing”conductor 112 a connected to the blade 151 (e.g., positive [+]electrode) and a second “return” conductor 112 b connected to theconductive jacket 472 (e.g., negative [−] electrode) of the clamp armassembly 451. In some embodiments, the generator 102 may provide a drivesignal to the transducer on the conductors 112 a, 112 b and/or overadditional conductors included in the cable 112. In one embodiment, RFvoltage v_(rf) is applied to the blade 151 to cause RF current i_(rf) toflow through the tissue 414. The second conductor 112 b provides thereturn path for the current i_(rf) back to the tissue impedance module402. The distal end of the return conductor 112 b is connected to theconductive jacket 472 such that the current i_(rf) can flow from theblade 151, through the tissue 414 positioned intermediate the conductivejacket 472 and the blade 151 and the conductive jacket 472 to the returnconductor 112 b. The impedance module 402 connects in circuit, by way ofthe first and second conductors 112 a, b. In one embodiment, the RFenergy may be applied to the blade 151 through the ultrasonic transducer114 and the waveguide (not shown). In some embodiments, the RF energyapplied to the tissue 414 for purposes of measuring the tissue impedanceZ_(t) is a low level subtherapeutic signal that does not contribute in asignificant manner, or at all, to the treatment of the tissue 414.

FIG. 6 illustrates one embodiment of an example electrosurgical device106 that may also be used for transection and sealing. According tovarious embodiments, the transection and sealing device 106 may comprisea handle assembly 130, an elongated shaft 165 and an end effector 132.The shaft 165 may be rigid, as shown, (e.g., for laparoscopic and/oropen surgical application) or flexible, (e.g., for endoscopicapplication). In various embodiments, the shaft 165 may comprise one ormore articulation points. The end effector 132 may comprise jaws 144having a first jaw member 167 and a second jaw member 169. A translatingmember 173 may extend within the shaft 165 from the end effector 132 tothe handle 130. At the handle 130, the shaft 165 may be directly orindirectly coupled to a jaw closure trigger 142 (FIG. 6).

The jaw members 167, 169 of the end effector 132 may comprise respectiveelectrodes 177, 179. The electrodes 177, 179 may be connected to thegenerator 102 via electrical leads 187 a, 187 b (FIG. 7) extending fromthe end effector 132 through the shaft 165 and handle 130 and ultimatelyto the generator 102 (e.g., by a multi-conductor cable 128). Thegenerator 102 may provide a drive signal to the electrodes 177, 179 tobring about a therapeutic effect to tissue present within the jawmembers 167, 169. The electrodes 177, 179 may comprise an activeelectrode and a return electrode, wherein the active electrode and thereturn electrode can be positioned against, or adjacent to, the tissueto be treated such that current can flow from the active electrode tothe return electrode through the tissue. As illustrated in FIG. 6, theend effector 132 is shown with the jaw members 167, 169 in an openposition.

FIGS. 7, 8, and 9 illustrate one embodiment of the end effector 132shown in FIG. 6. To close the jaws 144 of the end effector 132, aclinician may cause the jaw closure trigger 142 to pivot along arrow 183(FIG. 6) from a first position to a second position. This may cause thejaws 144 to open and close according to any suitable method. Forexample, motion of the jaw closure trigger 142 may, in turn, cause thetranslating member 173 to translate within a bore 185 of the shaft 165.A distal portion of the translating member 173 may be coupled to areciprocating member 197 such that distal and proximal motion of thetranslating member 173 causes corresponding distal and proximal motionof the reciprocating member. The reciprocating member 197 may haveshoulder portions 191 a, 191 b, while the jaw members 167, 169 may havecorresponding cam surfaces 189 a, 189 b. As the reciprocating member 197is translated distally from the position shown in FIG. 8 to the positionshown in FIG. 9, the shoulder portions 191 a, 191 b may contact the camsurfaces 189 a, 189 b, causing the jaw members 167, 169 to transition tothe closed position. Also, in various embodiments, the blade 175 may bepositioned at a distal end of the reciprocating member 197. As thereciprocating member 197 extends to the fully distal position shown inFIG. 9, the blade 175 may be pushed through any tissue present betweenthe jaw members 167, 169, in the process, severing it. In someembodiments, a strain gauge 166 or any other suitable pressure sensormay be placed on the jaw member 167 and/or the jaw member 169 to measurethe pressure placed on tissue by the respective jaw members 167, 169during tissue treatment (FIG. 8). Also, in some embodiments, one or bothof the jaw members 167, 169 may comprise a temperature sensor 168 forsensing a temperature of tissue between the jaw members 167, 169 (FIG.8). The temperature sensor 168 may be, for example, a thermocouple, aresistive temperature device, an infrared sensor, a bimetallic device,etc.

In use, a clinician may place the end effector 132 and close the jaws144 around a tissue bite to be acted upon, for example, by pivoting thejaw closure trigger 142 along arrow 183 as described. Once the tissuebite is secure between the jaws 144, the clinician may initiate theprovision of RF or other electro-surgical energy by the generator 102and through the electrodes 177, 179. The provision of RF energy may beaccomplished in any suitable way. For example, the clinician mayactivate the foot switch 120 (FIG. 14) of the generator 102 to initiatethe provision of RF energy. Also, for example, the handle 130 maycomprise one or more switches 181 that may be actuated by the clinicianto cause the generator 102 to begin providing RF energy. Additionally,in some embodiments, RF energy may be provided based on the position ofthe jaw closure trigger 142. For example, when the trigger 142 is fullydepressed (indicating that the jaws 144 are closed), RF energy may beprovided. Also, according to various embodiments, the blade 175 may beadvanced during closure of the jaws 144 or may be separately advanced bythe clinician after closure of the jaws 144 (e.g., after a RF energy hasbeen applied to the tissue).

FIGS. 10, 11, 12, 13 and 13A illustrate another embodiment of anelectrosurgical device 4106. Referring to FIG. 13A, the device 4106 maycomprise a handle assembly 4130, a shaft 4165 and an end effector 4132.The shaft 4165 may couple the end effector 4132 to the handle assembly4130. In some examples, the shaft 4165 may comprise an outer sheath4158. The end effector 4132, may be used with the electrosurgical device4106 and/or may be used that may be used with the electrosurgical device106 shown in FIG. 6. The end effector 4132 comprises first and secondjaw members 4167, 4169. The jaw members 4167, 4169 may compriserespective electrodes 4177, 4179 for providing electrosurgical energy totissue between the jaw members 4167, 4169. A knife 4137 may bealternately extendible and retractable through respective slots 4127,4129 in the jaw members 4167, 4169. In some examples, the knife 4137 mayomit shoulder portions for actuating the jaw members, as described abovewith respect to the end effector 132. For example, the jaw members 4167,4169 may be actuated by a jaw actuator independent of the blade 4137,such as the outer sheath 4158. In some examples, one or more of the jawmembers 4167, 4169 may comprise teeth 4143 for gripping tissue (FIG.12). Also, one or more of the jaw members 4167, 4169 may comprise a pin4133 positioned to ride within the slot 4127 of the opposite jaw member4167 to maintain alignment of the jaw members 4167, 4169 during theclosing and firing process (FIG. 12).

The handle assembly 4130 may comprise a jaw closure trigger 4142. Whenactuated by a clinician, the jaw closure trigger 4142 may retract a jawactuator, such as, for example, the outer sheath 4158, to close jawmembers 4167, 4169. The jaw closure trigger 4142 be coupled to a clamparm 4454. The clamp arm 4454 may be coupled to a yoke 4456. When the jawclosure trigger 4142 is actuated in the direction indicated by arrow4183, the yoke 4456 moves proximally and compresses a clamp spring 4406.Compression of the clamp spring 4406 retracts the jaw actuator totransition the jaw members 4167, 4169 from an open position to a closedposition. For example, the jaw actuator may comprise one or more pins orshoulder portions, similar to 191 a, 191 b, which may contact one ormore cam surfaces, similar to 189 a, 189 b, on the jaw members 4167,4169. In some examples, the jaw actuator may comprise one or more pinsthat ride in cam slots of the respective jaw members 4167, 4169.

The handle assembly 4130 may also comprise a firing trigger 4402. Thefiring trigger 4402 may be actuatable independent of the jaw closuretrigger 4142. The firing trigger 4402 may be coupled to a reciprocatingmember 4404. The reciprocating member 4404 may be coupled to the knife4137. For example, the knife 4137 may be positioned at a distal portionof the reciprocating member (FIG. 11). The firing trigger 4402 maycomprise a rack gear 4412 positioned to couple with a combination gear4460. The combination gear 4460 comprises a gear 4410 and a gear 4414coupled on a common axis. The gear 4414 may be in contact with the rackgear 4412. To actuate the firing trigger 4402, a clinician may depressthe firing trigger 4402 proximally. This may cause the firing trigger topivot about pivot point 4442. Actuation of the firing trigger 4402 inthe direction indicated by arrow 4183 may translate the rack gear,causing counter-clockwise rotation of the combination gear 4460. Thegear 4410 may interface with a rack gear 4408 coupled to thereciprocating member 4404. Counter-clockwise rotation of the gear 4410may translate the rack gear 4408 and the reciprocating member 4404distally, advancing the knife 4137 within the 4127, 4129 describedherein. An energy button 4416 may be depressed or otherwise actuated tobegin delivery of energy to the electrodes 4167, 4169. The energy button4416 may be any suitable type of button, switch, or similar device.

The electrosurgical instrument 4106 may also comprise a closure switch4450. The closure trigger 4142 may have a corresponding feature 4452such that when the closure trigger 4142 is actuated in a proximaldirection, the feature 4452 contacts and actuates the switch 4450.Actuation of the switch 4450 may indicate jaw closure. The feature 4452is illustrated as a protrusion extending proximally from a body of thejaw closure trigger 4142. Any suitable feature of the trigger 4142,however, may be positioned to contact the closure switch 4450.Additional details of electrosurgical devices similar to the 4106 andother devices that may be used in conjunction with the various featuresdescribed herein are provided in U.S. patent application Ser. No.14/075,863, filed on Nov. 8, 2013, which is incorporated herein byreference in its entirety.

FIG. 14 is a diagram of the surgical system 100 of FIG. 1. In variousembodiments, the generator 102 may comprise several separate functionalelements, such as modules and/or blocks. Different functional elementsor modules may be configured for driving the different kinds of surgicaldevices 104, 106. For example an ultrasonic generator module 108 maydrive an ultrasonic device, such as the ultrasonic device 104. Anelectrosurgery/RF generator module 110 may drive an electrosurgicaldevice 106, 4106. For example, the respective modules 108, 110 maygenerate respective drive signals for driving the surgical devices 104,106, 4106. In various embodiments, the ultrasonic generator module 108and/or the electrosurgery/RF generator module 110 each may be formedintegrally with the generator 102. Alternatively, one or more of themodules 108, 110 may be provided as a separate circuit moduleelectrically coupled to the generator 102. (The modules 108 and 110 areshown in phantom to illustrate this option.) Also, in some embodiments,the electrosurgery/RF generator module 110 may be formed integrally withthe ultrasonic generator module 108, or vice versa.

In accordance with the described embodiments, the ultrasonic generatormodule 108 may produce a drive signal or signals of particular voltages,currents, and frequencies, e.g. 55,500 cycles per second (Hz). The drivesignal or signals may be provided to the ultrasonic device 104, andspecifically to the transducer 114, which may operate, for example, asdescribed above. In some embodiments, the generator 102 may beconfigured to produce a drive signal of a particular voltage, current,and/or frequency output signal that can be stepped with high resolution,accuracy, and repeatability. Optionally, the tissue impedance module 402may be included separately or formed integrally with the ultrasonicgenerator module 108 to measure tissue impedance when utilizing anultrasonic device 104, for example, as described herein above.

In accordance with the described embodiments, the electrosurgery/RFgenerator module 110 may generate a drive signal or signals with outputpower sufficient to perform bipolar electrosurgery using radio frequency(RF) energy. In bipolar electrosurgery applications, the drive signalmay be provided, for example, to the electrodes of the electrosurgicaldevice 106, 4106, for example, as described above. Accordingly, thegenerator 102 may be configured for therapeutic purposes by applyingelectrical energy to the tissue sufficient for treating the tissue(e.g., coagulation, cauterization, tissue welding, etc.).

The generator 102 may comprise an input device 145 located, for example,on a front panel of the generator 102 console. The input device 145 maycomprise any suitable device that generates signals suitable forprogramming the operation of the generator 102. In operation, the usercan program or otherwise control operation of the generator 102 usingthe input device 145. The input device 145 may comprise any suitabledevice that generates signals that can be used by the generator (e.g.,by one or more processors contained in the generator) to control theoperation of the generator 102 (e.g., operation of the ultrasonicgenerator module 108 and/or electrosurgery/RF generator module 110). Invarious embodiments, the input device 145 includes one or more ofbuttons, switches, thumbwheels, keyboard, keypad, touch screen monitor,pointing device, remote connection to a general purpose or dedicatedcomputer. In other embodiments, the input device 145 may comprise asuitable user interface, such as one or more user interface screensdisplayed on a touch screen monitor, for example. Accordingly, by way ofthe input device 145, the user can set or program various operatingparameters of the generator, such as, for example, current (I), voltage(V), frequency (f), and/or period (T) of a drive signal or signalsgenerated by the ultrasonic generator module 108 and/orelectrosurgery/RF generator module 110.

The generator 102 may also comprise an output device 147 (FIG. 1)located, for example, on a front panel of the generator 102 console. Theoutput device 147 includes one or more devices for providing a sensoryfeedback to a user. Such devices may comprise, for example, visualfeedback devices (e.g., an LCD display screen, LED indicators), audiofeedback devices (e.g., a speaker, a buzzer) or tactile feedback devices(e.g., haptic actuators). Although certain modules and/or blocks of thegenerator 102 may be described by way of example, it can be appreciatedthat a greater or lesser number of modules and/or blocks may be used andstill fall within the scope of the embodiments. Further, althoughvarious embodiments may be described in terms of modules and/or blocksto facilitate description, such modules and/or blocks may be implementedby one or more hardware components, e.g., processors, Digital SignalProcessors (DSPs), Programmable Logic Devices (PLDs), ApplicationSpecific Integrated Circuits (ASICs), circuits, registers and/orsoftware components, e.g., programs, subroutines, logic and/orcombinations of hardware and software components.

In some embodiments, the ultrasonic generator drive module 108 andelectrosurgery/RF drive module 110 may comprise one or more embeddedapplications implemented as firmware, software, hardware, or anycombination thereof. The modules 108, 110 may comprise variousexecutable modules such as software, programs, data, drivers,application program interfaces (APIs), and so forth. The firmware may bestored in nonvolatile memory (NVM), such as in bit-masked read-onlymemory (ROM) or flash memory. In various implementations, storing thefirmware in ROM may preserve flash memory. The NVM may comprise othertypes of memory including, for example, programmable ROM (PROM),erasable programmable ROM (EPROM), electrically erasable programmableROM (EEPROM), or battery backed random-access memory (RAM) such asdynamic RAM (DRAM), Double-Data-Rate DRAM (DDRAM), and/or synchronousDRAM (SDRAM).

In some embodiments, the modules 108, 110 comprise a hardware componentimplemented as a processor for executing program instructions formonitoring various measurable characteristics of the devices 104, 106,4106 and generating a corresponding output drive signal or signals foroperating the devices 104, 106, 4106. In embodiments in which thegenerator 102 is used in conjunction with the ultrasonic device 104, thedrive signal may drive the ultrasonic transducer 114 in cutting and/orcoagulation operating modes. Electrical characteristics of the device104 and/or tissue may be measured and used to control operationalaspects of the generator 102 and/or provided as feedback to the user. Inembodiments in which the generator 102 is used in conjunction with anelectrosurgical device 106, 4106, the drive signal may supply electricalenergy (e.g., RF energy) to the end effector 132 in cutting, coagulationand/or desiccation modes. Electrical characteristics of the device 106,4106 and/or tissue may be measured and used to control operationalaspects of the generator 102 and/or provided as feedback to the user. Invarious embodiments, as previously discussed, the hardware componentsmay be implemented as DSP, PLD, ASIC, circuits, and/or registers. Insome embodiments, the processor may be configured to store and executecomputer software program instructions to generate the step functionoutput signals for driving various components of the devices 104, 106,4106, such as the ultrasonic transducer 114 and the end effectors 126,132.

The surgical devices 104, 106, 4106 described herein may be incorporatedinto unitary surgical systems comprising both a surgical device, such as104, 106, and 4106, and an integral generator. FIGS. 15-18 show variousembodiments of a surgical system 200 comprising an example unitaryelectrosurgical system 200. FIG. 15 shows a perspective view of oneexample embodiment of a surgical system 200 comprising a cordlesselectrical energy surgical instrument 210 with an integral generator(not shown in FIG. 15). The electrosurgical system 200 is similar to thesurgical system 100 (e.g., utilized with the electrosurgical device 106,4106). The electrosurgical system 200 can be configured to supplyenergy, such as electrical energy, ultrasonic energy, heat energy, orany combination thereof, to the tissue of a patient either independentlyor simultaneously as described in connection with FIGS. 1-14, forexample. The electrosurgical instrument 210 may utilize the end effector132 and elongated shaft 165 described herein with respect to FIGS. 6-9in conjunction with a cordless proximal handle 212. In one exampleembodiment, the handle 212 includes the integral generator circuit 220(see FIG. 16). The generator circuit 220, sometimes referred to hereinas a generator 220, performs a function substantially similar to that ofgenerator 102. In one example embodiment, the generator circuit 220 iscoupled to a controller or control circuit (e.g., 281 in FIG. 17). Inthe illustrated embodiment, the control circuit is integrated into thegenerator circuit 220. In other embodiments, the control circuit may beseparate from the generator circuit 220.

In one example embodiment, various electrodes in the end effector 126(e.g., 177, 179) may be coupled to the generator circuit 220. Thecontrol circuit 281 may be used to activate the generator 220, which mayserve as an electrical source. In various embodiments, the generator 220may comprise an RF source, an ultrasonic source, a direct currentsource, a microwave source, and/or any other suitable type ofthermogenic energy source, for example. For example, a direct currentsource may be utilized to power a heating element that could treattissue. In one example embodiment, a button 228 may be provided toactivate the generator circuit 220 to provide energy to the end effector126.

FIG. 16 shows a side-view of one example embodiment of the handle 212 ofthe cordless surgical instrument 210 with half of a first handle bodyremoved to illustrate various components within the second handle body234. The handle 212 may comprise a lever arm 221 (e.g., a trigger) whichmay be pulled along a path (similar to 183) around a pivot point. Thelever arm 221 may be coupled to an axially moveable member 278 disposedwithin the shaft 165 by a shuttle operably engaged to an extension oflever arm 221. In one example embodiment, the lever arm 221 defines ashepherd's hook shape comprising a distal trigger hook 221 a and aproximal trigger portion 221 b. As illustrated, the distal trigger hook221 a may have a first length while the proximal trigger portion 221 bmay have a second length with the second length greater than the firstlength.

In one example embodiment, the cordless electrosurgical instrumentcomprises a battery 237. The battery 237 provides electrical energy tothe generator circuit 220. The battery 237 may be any battery suitablefor driving the generator circuit 220 at the desired energy levels. Inone example embodiment, the battery 237 is a 1030 mAhr, triple-cellLithium Ion Polymer battery. The battery may be fully charged prior touse in a surgical procedure, and may hold a voltage of about 12.6V. Thebattery 237 may have two fuses fitted to the cordless electrosurgicalinstrument 210, arranged in line with each battery terminal. In oneexample embodiment, a charging port 239 is provided to connect thebattery 237 to a DC current source (not shown).

The generator circuit 220 may be configured in any suitable manner. Insome embodiments, the generator circuit comprises an RF drive andcontrol circuit 240 and a controller circuit 282. FIG. 17 shows oneembodiment of an RF drive and control circuit 240. FIG. 17 is a partschematic part block diagram showing the RF drive and control circuitry240 used in this embodiment to generate and control the RF electricalenergy supplied to the end effector 126. In this embodiment, the drivecircuitry 240 is a resonant mode RF amplifier comprising a parallelresonant network on the RF amplifier output and the control circuitryoperates to control the operating frequency of the electrosurgical drivesignal so that it is maintained at the resonant frequency of the drivecircuit, which in turn controls the amount of power supplied to the endeffector 126. The way that this is achieved will become apparent fromthe following description.

As shown in FIG. 17, the RF drive and control circuit 240 comprises theabove described battery 237 are arranged to supply, in this example,about 0V and about 12V rails. An input capacitor (C_(in)) 242 isconnected between the 0V and the 12V for providing a low sourceimpedance. A pair of FET switches 243-1 and 243-2 (both of which areN-channel in this embodiment to reduce power losses) is connected inseries between the 0V rail and the 12V rail. FET gate drive circuitry245 is provided that generates two drive signals—one for driving each ofthe two FET's 243. The FET gate drive circuitry 245 generates drivesignals that causes the upper FET (243-1) to be on when the lower FET(243-2) is off and vice versa. This causes the node 247 to bealternately connected to the 12V rail (when the FET 243-1 is switchedon) and the 0V rail (when the FET 243-2 is switched on). FIG. 8B alsoshows the internal parasitic diodes 248-1 and 248-2 of the correspondingFET's 243, which conduct during any periods that the FET's 243 are open.

As shown in FIG. 17, the node 247 is connected to an inductor-inductorresonant circuit 250 formed by inductor L_(s) 252 and inductor L_(m)254. The FET gate driving circuitry 245 is arranged to generate drivesignals at a drive frequency (f_(d)) that opens and crosses the FETswitches 243 at the resonant frequency of the parallel resonant circuit250. As a result of the resonant characteristic of the resonant circuit250, the square wave voltage at node 247 will cause a substantiallysinusoidal current at the drive frequency (f_(d)) to flow within theresonant circuit 250. As illustrated in FIG. 17, the inductor L_(m) 254is the primary of a transformer 255, the secondary of which is formed byinductor L_(sec) 256. The inductor L_(sec) 256 of the transformer 255secondary is connected to an inductor-capacitor-capacitor parallelresonant circuit 257 formed by inductor L₂ 258, capacitor C₄ 260, andcapacitor C₂ 262. The transformer 255 up-converts the drive voltage(V_(d)) across the inductor L_(m) 254 to the voltage that is applied tothe output parallel resonant circuit 257. The load voltage (V_(L)) isoutput by the parallel resonant circuit 257 and is applied to the load(represented by the load resistance R_(load) 259 in FIG. 8B)corresponding to the impedance of the forceps' jaws and any tissue orvessel gripped by the end effector 126. As shown in FIG. 8B, a pair ofDC blocking capacitors C_(bl1) 280-1 and C_(bl2) 280-2 is provided toprevent any DC signal being applied to the load 259.

In one embodiment, the transformer 255 may be implemented with a CoreDiameter (mm), Wire Diameter (mm), and Gap between secondary windings inaccordance with the following specifications:

Core Diameter, D (mm)

D=19.9×10-3

Wire diameter, W (mm) for 22 AWG wire

W=7.366×10-4

Gap between secondary windings, in gap=0.125

G=gap/25.4

In this embodiment, the amount of electrical power supplied to the endeffector 126 is controlled by varying the frequency of the switchingsignals used to switch the FET's 243. This works because the resonantcircuit 250 acts as a frequency dependent (loss less) attenuator. Thecloser the drive signal is to the resonant frequency of the resonantcircuit 250, the less the drive signal is attenuated. Similarly, as thefrequency of the drive signal is moved away from the resonant frequencyof the circuit 250, the more the drive signal is attenuated and so thepower supplied to the load reduces. In this embodiment, the frequency ofthe switching signals generated by the FET gate drive circuitry 245 iscontrolled by a controller 281 based on a desired power to be deliveredto the load 259 and measurements of the load voltage (V_(L)) and of theload current (I_(L)) obtained by conventional voltage sensing circuitry283 and current sensing circuitry 285. The way that the controller 281operates will be described in more detail below.

In one embodiment, the voltage sensing circuitry 283 and the currentsensing circuitry 285 may be implemented with high bandwidth, high speedrail-to-rail amplifiers (e.g., LMH6643 by National Semiconductor). Suchamplifiers, however, consume a relatively high current when they areoperational. Accordingly, a power save circuit may be provided to reducethe supply voltage of the amplifiers when they are not being used in thevoltage sensing circuitry 283 and the current sensing circuitry 285. Inone-embodiment, a step-down regulator (e.g., LT1502 by LinearTechnologies) may be employed by the power save circuit to reduce thesupply voltage of the rail-to-rail amplifiers and thus extend the lifeof the battery 237.

FIG. 18 shows the main components of the controller 281, according toone embodiment. In the embodiment illustrated in FIG. 18, the controller281 is a microprocessor based controller and so most of the componentsillustrated in FIG. 8c are software based components. Nevertheless, ahardware based controller 281 may be used instead. As shown, thecontroller 281 includes synchronous I,Q sampling circuitry 291 thatreceives the sensed voltage and current signals from the sensingcircuitry 283 and 285 and obtains corresponding samples which are passedto a power, V_(rms) and I_(rms) calculation module 293. The calculationmodule 293 uses the received samples to calculate the RMS voltage andRMS current applied to the load 259 (FIG. 8B; end effector 126 andtissue/vessel gripped thereby) and from them the power that is presentlybeing supplied to the load 259. The determined values are then passed toa frequency control module 295 and a medical device control module 297.The medical device control module 297 uses the values to determine thepresent impedance of the load 259 and based on this determined impedanceand a pre-defined algorithm, determines what set point power (P_(set))should be applied to the frequency control module 295. The medicaldevice control module 297 is in turn controlled by signals received froma user input module 299 that receives inputs from the user (for examplepressing buttons 228 or activating the control levers 221 on the handle212) and also controls output devices (lights, a display, speaker or thelike) on the handle 212 via a user output module 261.

The frequency control module 295 uses the values obtained from thecalculation module 293 and the power set point (P_(set)) obtained fromthe medical device control module 297 and predefined system limits (tobe explained below), to determine whether or not to increase or decreasethe applied frequency. The result of this decision is then passed to asquare wave generation module 263 which, in this embodiment, incrementsor decrements the frequency of a square wave signal that it generates by1 kHz, depending on the received decision. As those skilled in the artwill appreciate, in an alternative embodiment, the frequency controlmodule 295 may determine not only whether to increase or decrease thefrequency, but also the amount of frequency change required. In thiscase, the square wave generation module 263 would generate thecorresponding square wave signal with the desired frequency shift. Inthis embodiment, the square wave signal generated by the square wavegeneration module 263 is output to the FET gate drive circuitry 245,which amplifies the signal and then applies it to the FET 243-1. The FETgate drive circuitry 245 also inverts the signal applied to the FET243-1 and applies the inverted signal to the FET 243-2.

In various embodiments, the surgical devices 104, 106, 4106, 200 may beconfigured to provide to the generator 102, 220, an indication of thestate of the jaw or clamp arm. This may allow the generator 102, 220 tosense when the clinician has released a tissue bite after treatment. Forexample, after providing an energy cycle to a surgical device 104, 106,4106, 200, the generator 102, 220 may determine whether the clinicianhas released the treated tissue from between the jaw members or clamparm and blade based on whether the generator 102, 220 has received anindication that the jaw members or clamp arms have been opened since theenergy cycle (e.g., whether the jaw aperture has increased).

The surgical devices 104, 106, 4106, 200 may be configured to providethe generator 102, 220 with an indication of the state of the jawmembers or clamp arm in any suitable manner. For example, referring tothe ultrasonic surgical device 104, a proximity sensor 191 may bepositioned to provide the generator 102, 220 with an indication when theclamp arm 155 is opened or closed (FIG. 3). Any suitable proximitysensor may be used such as, for example, a capacitive proximity sensor,an optical proximity sensor, a magnetic proximity sensor, a mechanicalswitch, a Hall effect sensor, etc. Although the proximity sensor 191 isshown coupled to the shaft 153, the proximity sensor 191 may be placedat any position on the shaft 153, clamp arm 155 or other component thatmoves relative to the clamp arm 155 or blade 151. Additionally, oralternatively, the generator 102, 220 may be in communication with theelectrodes 157, 159. For example, a closed circuit between theelectrodes 157, 159 may indicate that tissue is present while an opencircuit between the electrodes 157, 159 may indicate that no tissue ispresent. Additionally or alternatively, the generator 102, 220 may be incommunication with the pressure sensor 156. For example, an increase inpressure may indicate that the clamp arm 155 is closed or closing whilea decrease in pressure may indicate that the clamp arm 155 is open oropening. Additionally or alternatively, the generator 102, 220 may be incommunication with the temperature sensor 156. For example, a decreasein temperature may indicate that tissue has been removed from betweenthe clamp arm 155 and the blade 151. In some embodiments, a sensor 193may be positioned in the handle 116 to sense the position of the trigger138 (FIG. 2) or of any transmission components between the trigger 138and the clamp arm 155. The sensor 193 may be any suitable type of sensorincluding, for example, a proximity sensor, a switch, etc. For example,the position of the trigger 138 and transmission components maycorrespond to the position of the clamp arm 155.

Referring to the various surgical devices 104, 106, 4106, 200, theposition of the jaw members (or clamp arm) may be determined in asimilar manner. For example, a proximity sensor 195 may be positioned atthe end effector 132 (FIG. 8) to sense when the jaw members 167, 169 arein proximity to one another (e.g., closed). Proximity or switch sensorsmay also be positioned in the respective handle assemblies. The handleassembly 130 (FIG. 6) shows an example of a proximity sensor 199positioned therein. The proximity sensor 199 may be positioned to senseactuation of the jaw closure trigger 142 and/or an intermediatecomponent directly or indirectly in contact with the jaw closure trigger142. In addition to or instead of the proximity sensor 199, one or moresimilar proximity sensors (not shown) may be positioned in the shaft 165(FIG. 6), 4165 (FIG. 13A). For example, a shaft-positioned proximitysensor may sense a position of the closure trigger 142, 4142, jawmembers 167, 169, 4167, 4169, reciprocating member 197, 139, 173, 4404,etc. In some examples, a proximity sensor may comprise a switch, such as4450 (FIG. 13A).

In addition to or instead of using proximity sensors, the generator 102,220 may be in communication with one or more of the pressure sensor 166,and/or the temperature sensor 168 to sense the closure state of the jawmembers 167, 169, for example, as described herein with respect to theultrasonic device 104. In some examples, the generator 102, 220 may alsodetermine whether the jaws are closed by sending a signal to theelectrodes 177, 179. If a closed circuit is detected, it may indicatethat the jaw members 167, 169 are closed either on each other or ontissue.

According to various embodiments, the generator 102, 220 may providepower to a tissue bite according to one or more power curves. A powercurve may define a relationship between power delivered to the tissueand the impedance of the tissue. For example as the impedance of thetissue changes (e.g., increases) during coagulation, the power providedby the generator 102, 220 may also change (e.g., decrease) according tothe applied power curve. Power curves may be applied in any suitablemanner. For example, the generator 102, 220, may manipulatecharacteristics of the drive signal provided to the surgical device tobring about the level of power indicated by the power curve. Also, insome examples, a power curve may be implemented in terms of other drivesignal characteristics. For example, a power curve may specify voltages,currents, frequencies, duty cycles, etc. corresponding to tissueimpedance.

Different power curves may be particularly suited, or ill-suited, todifferent types and/or sizes of tissue bites. Aggressive power curves(e.g., power curves calling for high power levels) may be suited forlarge tissue bites. When applied to smaller tissue bites, such as smallvessels, more aggressive power curves may lead to exterior searing.Exterior searing may reduce the coagulation/weld quality at the exteriorand can also prevent complete coagulation of interior portions of thetissue. Similarly, less aggressive power curves may fail to achievehemostasis when applied to larger tissue bites (e.g., larger bundles).

FIG. 19 illustrates one embodiment of a chart 1300 showing example powercurves 1306, 1308, 1310. The chart 1300 comprises an impedance axis 1302illustrating increasing potential tissue impedances from left to right.A power axis 1304 illustrates increasing power from down to up. Each ofthe power curves 1306, 1308, 1310 may define a set of power levels, onthe power axis 1304, corresponding to a plurality of potential sensedtissue impedances, in the impedance axis 1302. In general, power curvesmay take different shapes, and this is illustrated in FIG. 19. Powercurve 1306 is shown with a step-wise shape, while power curves 1308,1310 are shown with curved shapes. It will be appreciated that powercurves utilized by various embodiments may take any usable continuous ornon-continuous shape. The rate of power delivery or aggressiveness of apower curve may be indicated by its position on the chart 1300. Forexample, power curves that deliver higher power for a given tissueimpedance may be considered more aggressive. Accordingly, between twopower curves, the curve positioned highest on the power axis 1304 may bethe more aggressive. It will be appreciated that some power curves mayoverlap.

The aggressiveness of two power curves may be compared according to anysuitable method. For example, a first power curve may be considered moreaggressive than a second power curve over a given range of potentialtissue impedances if the first power curve has a higher delivered powerover the range. Delivered power over the range of potential tissueimpedances may be measured in any suitable manner. For example, thedelivered power over the range may be represented by an area under thepower curve over the range or, when a power curve is expresseddiscretely, a sum of the power values for the power curve over the setof potential tissue impedances.

According to various embodiments, the algorithms described herein may beused with any kind of surgical device (e.g., ultrasonic device 104,electrosurgical device 106, 4106, 200). In embodiments utilizing anultrasonic device 104, tissue impedance readings may be taken utilizingelectrodes 157, 159 and/or utilizing the clamp arm assembly 451described herein with respect to FIGS. 4 and 5. With an electrosurgicaldevice, such as 106, 200, 4106, tissue impedance readings may be takenutilizing first and second electrodes 177, 179.

In some embodiments, an electrosurgical device 104 may comprise apositive temperature coefficient (PTC) material positioned between oneor both of the electrodes 177, 179, 4177, 4179 and the tissue bite. ThePTC material may have an impedance profile that remains relatively lowand relatively constant until it reaches a threshold or triggertemperature, at which point the impedance of the PTC material mayincrease. In use, the PTC material may be placed in contact with thetissue while power is applied. The trigger temperature of the PTCmaterial may be selected such that it corresponds to a tissuetemperature indicating the completion of welding or coagulation.Accordingly, as a welding or coagulation process is completed, theimpedance of the PTC material may increase, bringing about acorresponding decrease in power actually provided to the tissue.

During the coagulation process, tissue impedance may generally increase.In some embodiments, tissue impedance may display a sudden impedanceincrease indicating successful coagulation. The increase may be due tophysiological changes in the tissue, a PTC material reaching its triggerthreshold, etc., and may occur at any point in the coagulation process.The amount of energy that may be required to bring about the suddenimpedance increase may be related to the thermal mass of the tissuebeing acted upon. The thermal mass of any given tissue bite, in turn,may be related to the type and amount of tissue in the bite.

Various embodiments may utilize this sudden increase in tissue impedanceto select an appropriate power curve for a given tissue bite. Forexample, the generator 102, 220 may select and apply successively moreaggressive power curves until the tissue impedance reaches an impedancethreshold indicating that the sudden increase has occurred. For example,reaching the impedance threshold may indicate that coagulation isprogressing appropriately with the currently applied power curve. Theimpedance threshold may be a tissue impedance value, a rate of change oftissue impedance, and/or a combination of impedance and rate of change.For example, the impedance threshold may be met when a certain impedancevalue and/or rate of change are observed. According to variousembodiments, different power curves may have different impedancethresholds, as described herein.

FIG. 20 illustrates one embodiment of a process flow 1330 for applyingone or more power curves to a tissue bite. The process flow 1330 may beapplied as all or a part of an energy cycle performed by a surgicaldevice on tissue. In the process flow 1330, any suitable number of powercurves may be used. The power curves may be successively applied inorder of aggressiveness until one of the power curves drives the tissueto the impedance threshold. When the tissue is driven to the impedancethreshold the energy cycle may be terminated. At 1332, the generator102, 220 may apply a first power curve. According to variousembodiments, the first power curve may be selected to deliver power at arelatively low rate. For example, the first power curve may be selectedto avoid tissue searing with the smallest and most vulnerable expectedtissue bites.

The first power curve may be applied to the tissue in any suitablemanner. For example, the generator 102, 220 may generate a drive signalimplementing the first power curve. The power curve may be implementedby modulating the power of the drive signal. The power of the drivesignal may be modulated in any suitable manner. For example, the voltageand/or current of the signal may be modulated. Also, in variousembodiments, the drive signal may be pulsed. For example, the generator102, 220 may modulate the average power by changing the pulse width,duty cycle, etc. of the drive signal. The drive signal may be providedto the first and second electrodes 177, 179, 417, 4179 of theelectrosurgical device 106. In some embodiments the drive signalimplementing the first power curve may be provided to an ultrasonictransducer 114 of the ultrasonic device 104 described above.

While applying the first power curve, the generator 102, 220 may monitorthe total energy provided to the tissue. The impedance of the tissue maybe compared to the impedance threshold at one or more energy thresholds.There may be any suitable number of energy thresholds, which may beselected according to any suitable methodology. For example, the energythresholds may be selected to correspond to known points where differenttissue types achieve the impedance threshold. At 1334, the generator102, 220 may determine whether the total energy delivered to the tissuehas met or exceeded a first energy threshold. If the total energy hasnot yet reached the first energy threshold, the generator 102, 220 maycontinue to apply the first power curve at 1332.

If the total energy has reached the first energy threshold, thegenerator 102, 220 may determine whether the impedance threshold hasbeen reached (1336). As described above, the impedance threshold may bea predetermined rate of impedance change (e.g., increase) apredetermined impedance, or combination of the two. If the impedancethreshold is reached, the generator 102, 220 may continue to apply thefirst power curve at 1332. For example, reaching the impedance thresholdin the first power curve may indicate that the aggressiveness of thefirst power curve is sufficient to bring about suitable coagulation orwelding.

In the event that the impedance threshold is not reached at 1336, thegenerator 102, 220 may increment to the next most aggressive power curveat 1338 and apply the power curve as the current power curve at 1332.When the next energy threshold is reached at 1334, the generator 102,220 again may determine whether the impedance threshold is reached at1336. If it is not reached, the generator 102, 220 may again incrementto the next most aggressive power curve at 1338 and deliver that powercurve at 1332.

The process flow 1330 may continue until terminated. For example, theprocess flow 1330 may be terminated when the impedance threshold isreached at 1336. Also, for example, the process flow 1330 may terminateupon the exhaustion of all available power curves. Any suitable numberof power curves may be used. If the most aggressive power curve fails todrive the tissue to the impedance threshold, the generator 102, 220 maycontinue to apply the most aggressive power curve until the energy cycleis otherwise terminated (e.g., by a clinician or upon reaching a finalenergy threshold).

According to various embodiments, the process flow 1330 may continueuntil tissue impedance reaches a termination impedance threshold. Thetermination impedance threshold may indicate that coagulation and/orwelding is complete. For example, the termination impedance thresholdmay be based on one or more of tissue impedance, tissue temperature,tissue capacitance, tissue inductance, elapsed time, etc. These may be asingle termination impedance threshold or, in various embodiments,different power curves may have different termination impedancethresholds. According to various embodiments, different power curves mayutilize different impedance thresholds. For example, the process flow1330 may transition from a first to a second power curve if the firstpower curve has failed to drive the tissue to a first tissue impedancethreshold and may, subsequently, shift from the second to a third powercurve if the second power curve has failed to drive the tissue to asecond impedance threshold.

FIG. 21 illustrates one embodiment of a chart 1380 showing example powercurves 1382, 1384, 1386, 1388 that may be used in conjunction with theprocess flow 1330. Although four power curves 1382, 1384, 1386, 1388 areshown, it will be appreciated that any suitable number of power curvesmay be utilized. Power curve 1382 may represent the least aggressivepower curve and may be applied first. If the impedance threshold is notreached at the first energy threshold, then the generator 102, 220 mayprovide the second power curve 1384. The other power curves 1386, 1388may be utilized, as needed, for example in the manner described above.

As illustrated in FIG. 21, the power curves 1382, 1384, 1386, 1388 areof different shapes. It will be appreciated, however, that some or allof a set of power curves implemented by the process flow 1330 may be ofthe same shape. FIG. 22 illustrates one embodiment of a chart showingexample common shape power curves 1392, 1394, 1396, 1398 that may beused in conjunction with the process flow 1330. According to variousembodiments, common shape power curves, such as 1392, 1394, 1396, 1398may be constant multiples of one another. Accordingly, the generator102, 220 may implement the common shape power curves 1392, 1394, 1396,1398 by applying different multiples to a single power curve. Forexample, the curve 1394 may be implemented by multiplying the curve 1392by a first constant multiplier. The curve 1396 may be generated bymultiplying the curve 1392 by a second constant multiplier. Likewise,the curve 1398 may be generated by multiplying the curve 1392 by a thirdconstant multiplier. Accordingly, in various embodiments, the generator102, 220 may increment to a next most aggressive power curve at 1338 bychanging the constant multiplier.

According to various embodiments, the process flow 1330 may beimplemented by a digital device (e.g., a processor, digital signalprocessor, field programmable gate array (FPGA), etc.) of the generator102, 220. FIGS. 23-25 illustrate process flows describing routines thatmay be executed by a digital device of the generator 102, 220 togenerally implement the process flow 1330 described above. FIG. 23illustrates one embodiment of a routine 1340 for preparing the generator102, 220 to act upon a new tissue bite. The activation or start of thenew tissue bite may be initiated at 1342. At 1344, the digital devicemay point to a first power curve. The first power curve, as describedabove, may be the least aggressive power curve to be implemented as apart of the process flow 1330. Pointing to the first power curve maycomprise pointing to a deterministic formula indicating the first powercurve, pointing to a look-up table representing the first power curve,pointing to a first power curve multiplier, etc.

At 1346, the digital device may reset an impedance threshold flag. Asdescribed below, setting the impedance threshold flag may indicate thatthe impedance threshold has been met. Accordingly, resetting the flagmay indicate that the impedance threshold has not been met, as may beappropriate at the outset of the process flow 1330. At 1348, the digitaldevice may continue to the next routine 1350.

FIG. 24 illustrates one embodiment of a routine 1350 that may beperformed by the digital device to monitor tissue impedance. At 1352,load or tissue impedance may be measured. Tissue impedance may bemeasured according to any suitable method and utilizing any suitablehardware. For example, according to various embodiments, tissueimpedance may be calculated according to Ohm's law utilizing the currentand voltage provided to the tissue. At 1354, the digital device maycalculate a rate of change of the impedance. The impedance rate ofchange may likewise be calculated according to any suitable manner. Forexample, the digital device may maintain prior values of tissueimpedance and calculate a rate of change by comparing a current tissueimpedance value or values with the prior values. Also, it will beappreciated that the routine 1350 assumes that the impedance thresholdis a rate of change. In embodiments where the impedance threshold is nota rate of change, 1354 may be omitted. If the tissue impedance rate ofchange (or impedance itself) is greater than the threshold (1356), thenthe impedance threshold flag may be set. The digital device may continueto the next routing at 1360.

FIG. 25 illustrates one embodiment of a routine 1362 that may beperformed by the digital device to provide one or more power curves to atissue bite. At 1364, power may be delivered to the tissue, for example,as described above with respect to 1334 of FIG. 20. The digital devicemay direct the delivery of the power curve, for example, by applying thepower curve to find a corresponding power for each sensed tissueimpedance, modulating the corresponding power onto a drive signalprovided to the first and second electrodes 177, 179, the transducer114, etc.

At 1366, the digital device may calculate the total accumulated energydelivered to the tissue. For example, the digital device may monitor thetotal time of power curve delivery and the power delivered at each time.Total energy may be calculated from these values. At 1368, the digitaldevice may determine whether the total energy is greater than or equalto a next energy threshold, for example, similar to the manner describedabove with respect to 1334 of FIG. 20. If the next energy threshold isnot met, the current power curve may continue to be applied at 1378 and1364.

If the next energy threshold is met at 1368, then at 1370, the digitaldevice may determine whether the impedance threshold flag is set. Thestate of the impedance threshold flag may indicate whether the impedancethreshold has been met. For example, the impedance threshold flag mayhave been set by the routine 1350 if the impedance threshold has beenmet. If the impedance flag is not set (e.g., the impedance threshold isnot met), then the digital device may determine, at 1372, whether anymore aggressive power curves remain to be implemented. If so, thedigital device may point the routine 1362 to the next, more aggressivepower curve at 1374. The routine 1362 may continue (1378) to deliverpower according to the new power curve at 1364. If all available powercurves have been applied, then the digital device may disablecalculating and checking of accumulated energy for the remainder of thetissue operation at 1376.

If the impedance flag is set at 1370 (e.g., the impedance threshold hasbeen met), then the digital device may disable calculating and checkingof accumulated energy for the remainder of the tissue operation at 1376.It will be appreciated that, in some embodiments, accumulated energycalculation may be continued, while 1370, 1372, 1374, and 1376 may bediscontinued. For example, the generator 102, 220 and/or digital devicemay implement an automated shut-off when accumulated energy reaches apredetermined value.

FIG. 26 illustrates one embodiment of a process flow 1400 for applyingone or more power curves to a tissue bite. For example, the process flow1400 may be implemented by the generator 102, 220 (e.g., the digitaldevice of the generator 102, 220). At 1402, the generator 102, 220 maydeliver a power curve to the tissue. The power curve may be derived byapplying a multiplier to a first power curve. At 1404, the generator102, 220 may determine if the impedance threshold has been met. If theimpedance threshold has not been met, the generator 102, 220 mayincrease the multiplier (e.g., as a function of the total appliedenergy). This may have the effect of increasing the aggressiveness ofthe applied power curve. It will be appreciated that the multiplier maybe increased periodically or continuously. For example, the generator102, 220 may check the impedance threshold (1404) and increase themultiplier (1406) at a predetermined periodic interval. In variousembodiments, the generator 102, 220 may continuously check the impedancethreshold (1404) and increase the multiplier (1406). Increasing themultiplier as a function of total applied energy may be accomplished inany suitable manner. For example, the generator 102, 220 may apply adeterministic equation that receives total received energy as input andprovides a corresponding multiplier value as output. Also, for example,the generator 102, 220 may store a look-up table that comprises a listof potential values for total applied energy and correspondingmultiplier values. According to various embodiments, the generator 102,220 may provide a pulsed drive signal to tissue (e.g., via one of thesurgical devices 104, 106, 200, 4106). According to various embodiments,when the impedance threshold is met, the multiplier may be heldconstant. The generator 102, 220 may continue to apply power, forexample, until a termination impedance threshold is reached. Thetermination impedance threshold may be constant, or may depend on thefinal value of the multiplier.

According to various embodiments, a surgical system may be configured toapply energy to tissue according to a segmented power curve. Accordingto a segmented power curve, the surgical system (e.g., a generator 102,220 thereof) may apply a first power curve when tissue impedance is inone of a set of first power curve segments and a second power curve whentissue impedance is in one of a set of second power curve segments. Thefirst and second power curves may have any suitable shape, for example,as described herein. In various embodiments, the second power curve maybe less aggressive than the first power curve over a range ofimpedances. For example, the second power curve may be less aggressivethan the first power curve over the range of impedances actuallyexhibited by the tissue during the course of an energy cycle (e.g., asreceived by the generator 102, 220). In some examples, the second powercurve may be less aggressive than the first power curve over the rangeof impedances expected to be exhibited by tissue in general, by tissueof the specific type being treated, etc. In some embodiments, the secondpower curve is a constant (e.g., 0-5 Watts or another suitable value).In this way, when tissue impedance is in one of the first power curvesegments, the generator 102, 220 may provide a high energy level thatadvances the coagulation of the tissue quickly and drives tissueimpedance up. When tissue impedance passes into a second power curvesegment, the generator 102, 220 may reduce the energy level (e.g., tobetween 0 and 5 Watts). This may slow the rate of impedance increase,which can lead to better sealing outcomes.

In some embodiments, first and second power curve segments may bedescribed by a ratio of the sum of first power curve segment widths(e.g., in ohms) to the sum of second power curve segment widths over alltissue impedances or a range of tissue impedances. The ratio maydescribe the tissue impedance range over which the segmented power curveis actually applied (e.g., as measured by the surgical system) or arange over which the segmented power curve is expected to be applied.The expected range may be determined, for example, based on impedancesmeasured over prior applications of the segmented power curve or similarsegmented power curves. In some examples, the ratio may be taken over asingle first power curve segment and a single second power curvesegment. A segmented power curve for driving tissue impedance up quicklymay have a relatively high ratio of first power curve segment width tosecond power curve segment width. A segmented power curve for drivingtissue impedance up more slowly may have a lower ratio. Any suitableratio may be used in a segmented drive signal. In some examples, theratio may have a value between 1/10 and 10. In some examples, the ratiomay have a value between ⅓ and 3.

Additionally, first and second power curve segments may be placedaccording to any suitable pattern. In some embodiments, first and secondpower curve segments are equally spaced across tissue impedances. Firstpower curve segments, for example, may have a constant first width.Second power curve segments may have a constant second width. In someembodiments, first power curve segment widths may vary across tissueimpedances, as may second power curve segment widths. Also, first andsecond power curve segments may be irregularly spaced according to anysuitable pattern.

FIG. 27 illustrates one embodiment of a segmented power curve 3000. InFIG. 27, the horizontal axis 3002 represents tissue impedance (Z) whilethe vertical axis 3004 represents power (3006), current (3008) andvoltage (3010) delivered to tissue according to the segmented powercurve 3000. First power curve segments 3013 are ranges of tissueimpedance at which the generator 102, 220 applies a first power curve.Second power curve segments 3012 are ranges of tissue impedance at whichthe generator 102, 220 applies a second power curve. For the examplepower curve 3000, the first power curve provides a maximum power of 200Watts when the tissue impedance is below fifty ohms and then graduallyreduces its power level as tissue impedance increases. The second powercurve is a constant 5 Watts. Below about 80 ohms, the segmented powercurve 3000 is in a first power curve segment 3013. Between about 80 ohmsand 320 ohms, the first and second power curve segments 3013, 3012alternate regularly with a ratio of first power curve segment widths3013 to second power curve segment widths 3012 that is about one (1).

FIG. 28 illustrates an alternative embodiment of a segmented power curve3020. The segmented power curve 3020 uses the same first and secondpower curves as the example segmented power curve 3000. The segmentedpower curve 3020, however, utilizes a larger number of smaller segments3012, 3013. Below about 60 ohms, the segmented power curve 3020 is in afirst power curve segment 3013. Between about 60 ohms and 320 ohms, thefirst and second power curve segments 3013, 3012 alternate regularlywith a ratio of the first power curve segment widths 3013 to the secondpower curve segment widths 3012 that is about one third (⅓).

FIG. 29 illustrates a plot 3050 showing an implementation of thesegmented power curve 3020 according to one embodiment. In the plot3050, the horizontal axis 3052 represents time while the vertical axis3054 shows power 3058 and tissue impedance 3056. An energy cycle beginswhen time is equal to zero (e.g., the generator 102, 220 begins to applyenergy to tissue). Between zero (0) and about 0.45 seconds, tissueimpedance 3056 remains below about 60 ohms and the surgical systemremains in the initial first power curve segment 3013 where a maximumpower of 200 Watts is provided (e.g., power 3058). Between zero (0) andabout 0.45 seconds, tissue impedance 3056 initially falls and thenrises, forming what is sometimes referred to the “bathtub” portion ofthe impedance plot 3056. After about 0.45 seconds, tissue impedance 3056exceeds about 60 ohms, causing a transition into an initial second powercurve segment 3012. As the power is cut according to the second powercurve, the impedance drops below about 60 ohms and back into the initialfirst power curve segment 3013. The impedance 3056 continues to rise (infirst power curve segments 3013) and fall (in second power curvesegments 3012), but trending towards higher impedance peaks in the firstpower curve segments 3013. This may continue until an end-of-cycle eventoccurs (e.g., a threshold impedance is reached).

FIG. 30 illustrates a state diagram showing one embodiment of a statediagram that may be implemented by a surgical system (e.g., a generator102, 220 thereof) to execute a segmented power curve, such as 3000,3020. During execution of the segmented power curve, the generator 102,220 may be in have a first power curve state 3032 and a second powercurve state 3034. When in the first power curve state 3032, thegenerator 102, 220 may provide a first power curve 3036 that may be anysuitable power curve including, for example, those described herein.When in the second power curve state, the generator 102, 220 may providea second power curve 3038. The second power curve 3038 may be anysuitable power curve including, for example, those described herein. Invarious embodiments, the second power curve 3038 may be a constant powerlevel, as shown in FIGS. 27 and 28. The constant power level may be anysuitable power level including, for example, between 0 Watts and 5Watts. Although the second power curve 3038 is a constant, otherexamples may use any suitable power curve in the second power curvestate. In some embodiments, the second power curve 3038 is lessaggressive than the first power curve 3032.

The generator 102, 220 may transition 3040 between the first power curvestate 3032 and the second power curve state 3034 according to a statetransition function 3042. Referring to the state transition function3042, the horizontal axis 3002 corresponds to tissue impedance while thevertical axis 3044 corresponds to the state of the generator 120. Thehigh (H) state on the axis 3044 corresponds to the first power curvestate 3032, while the low (L) state on the axis 3044 corresponds to thesecond power curve state 3034. For example, impedance ranges for whichthe state transition function 3042 is high may correspond to the firstpower curve segments 2012 in FIGS. 27 and 28. Impedance ranges for whichthe state transition function 3042 is low may correspond to second powercurve segments 3012. The high/low ratio of the state transition functionmay correspond to the ratio of first power curve segment widths tosecond power curve segment widths described above. To apply a segmentedpower curve, the generator 102, 220 may monitor tissue impedance andfind a value for the state transition function 3042. If the statetransition function 3042 is high, the generator 102, 220 may apply thefirst power curve 3036. If the state transition function 3042 is low,the generator 102, 220 may apply the second power curve 3038.

FIG. 31 illustrates a flow chart showing one embodiment of a processflow 3050 that may be executed by a surgical system (e.g., a generator102, 220 thereof) to execute a segmented power curve, such as 3000,3020. For example, the process flow 3050 may represent an energy cycle.At the beginning of the energy cycle, at 3054, the generator 102, 220may provide the first power curve to tissue. At 3056, the generator 102,220 may receive a measurement of the impedance of tissue being actedupon by the first power curve. In some embodiments utilizing anultrasonic surgical device, such as 104, the impedance may be animpedance of the transducer. At 3058, the generator 102, 220 maydetermine whether the received impedance measurement indicates a secondpower curve segment. If no, the generator 102, 220 may continue toprovide the first power curve at 3054. If yes, the generator 102, 220may provide the second power curve at 3060. Whether starting from action3054 or from action 3060, the generator 102, 220 may periodicallyexecute 3056 and 3058 to determine whether to switch power curves. Theprocess flow 3050 may conclude, for example, when the tissue impedanceor other property indicates the end of the energy cycle.

In some examples, a segmented power curve may implemented utilizing alook-up table or other suitable mechanism for storing tissue impedancesand corresponding drive signal characteristics. For example, FIG. 32illustrates a flow chart showing one embodiment of a process flow 3070that may be executed by a surgical system (e.g., a generator 102, 220thereof) to execute a segmented power curve, such as 3000, 3020, using alook-up table. Instead of alternately applying first and second powercurves, the generator 102, 220 may apply a consolidated segmented powercurve indicated by a look-up table. At 3072, the generator 102, 220 mayreceive an indication of the impedance of tissue being treated by theend effector. At 3074, the generator 102, 220 may receive acorresponding drive signal characteristic (e.g., power, voltage,current, etc.). For example, the generator 102, 220 may store a look-uptable or other mechanism that stores tissue impedances and correspondingdrive signal characteristics. Drive signal characteristics indicated bythe look-up table may incorporate both the first power curve and thesecond power curve described herein. For example, for impedancescorresponding to a first power curve segment, the look-up table mayreturn a drive signal characteristic consistent with the first powercurve. For impedances corresponding to a second power curve segment, thelook-up table may return a drive signal characteristic consistent withthe second power curve. At 3076, the generator 102 may apply thereceived drive signal characteristic to the end effector. The processflow 3070 may be executed, for example, during the provision of anenergy cycle. In some examples, it may be executed continuously untiltermination of the energy cycle.

In various embodiments, the surgical system (e.g., the generator 102,220 thereof) may be programmed to modify the signal provided to tissueif a clinician requests a second or subsequent energy cycle on the sametissue bite. An energy cycle may represent a single instance in whichenergy is applied to a tissue. For example, FIGS. 20, 26, 30 and 31illustrate flow charts and/or state diagrams setting forth energydelivery algorithms that may be applied in an energy cycle. An energycycle may conclude when energy provision to the tissue ceases, forexample, when the tissue impedance or other indicator reaches athreshold value or an energy delivery algorithm otherwise terminates.

Many energy cycles are designed to operate on tissue that has not yetbeen treated. Some clinicians, however, prefer to apply multiple energycycles to the same piece of tissue in contact with the end effector(e.g., tissue bite). Applying a second or subsequent energy cycle to thesame tissue bite, however, can sometimes damage tissue by applyingexcessive energy. Accordingly, the generator 102, 220 may be programmedto modify a drive signal provided to electrosurgical electrodes and/oran ultrasonic transducer if the generator determines that the endeffector is in contact with tissue that has already been treated by aprevious energy cycle.

FIG. 33 illustrates a flow chart 3100 showing one embodiment of aprocess flow 3100 for modifying a drive signal when a previous energycycle has already been applied to tissue. The process flow 3100 may beexecuted by a surgical system with any suitable type of surgical deviceincluding, for example, the ultrasonic surgical device 104 and/or theelectrosurgical devices 106, 4106, 200 described herein. At 3102, thesurgical system (e.g., a generator 102, 220 thereof) may receive anindication of an energy cycle request from a clinician. The clinicianmay request an energy cycle in any suitable manner. For example,referring to the ultrasonic surgical device 104, the clinician mayrequest an energy cycle by actuating one or more of buttons 136 a, 136b, 136 c (FIG. 2). In some examples, the clinician may request an energycycle by actuating a button on the surgical device (e.g., 181, 4412, 136a, 136 b, 136 c).

At 3104, the generator 102, 220 may determine whether the end effectorof the surgical device is in contact with tissue that has already beentreated. The generator 102, 220 may make this determination in anysuitable way. For example, the generator 102, 220 may determine whetherthe end effector has released the last tissue to be treated. Release maybe sensed in any suitable manner. For example, the generator 102, 220may determine whether electrosurgical jaws 167, 169 or an ultrasonicclamp arm 155 have been opened, as described herein. In some examples,the generator 102, 220 may monitor a property of the end effector, suchas temperature. If the temperature of the end effector is above athreshold value, it may indicate that the tissue present has alreadybeen treated. In some examples, the generator 102, 220 may monitor animpedance between electrodes in the end effector, such as 157, 159 ofthe end effector 126, electrodes 177, 179 of the end effector 132, theelectrodes 4177, 4179 of the end effector 4132, etc. For example, afteran energy cycle, the generator 102, 220 may provide a non-therapeuticsignal to the electrodes and monitor whether an open circuit isdetected. An open circuit may be detected, for example, if the impedanceexceeds a threshold value, if the current between the electrodes fallsbelow a threshold value, etc. If an open circuit is detected after anenergy cycle, the generator 102, 220 may determine that the end effectoris no longer in contact with the tissue that was treated during theenergy cycle. If no open circuit is detected after the energy cycle, thegenerator 102, 220 may determine that the end effector is still incontact with the tissue that was treated during the energy cycle. Insome examples, the generator 102, 220 may monitor a pressure exertedbetween members of the end effector (e.g., between jaw members 167, 169or 4167, 4169, between a clamp arm 155 and blade 151, etc.). Thepressure may be sensed, for example, by one or more pressure sensors156, 166, as described herein. If the generator 102, 220 determinesthere no reduction in pressure below a threshold pressure level sincethe previous energy cycle was completed, it may determine that thetissue contacting the end effector has been previously treated.

If the tissue at the end effector has not been treated, then thegenerator 102, 220 may, at 3108, apply the requested energy cycle. Ifthe tissue at the end effector has been treated, then the generator 102,220 may, at 3106, apply a modified energy cycle. For example, becausethe tissue has already been treated, the generator 102, 220 may modifythe requested energy cycle to reduce the total energy delivered duringthe energy cycle.

The energy cycle may be modified in any suitable manner. In someexamples, the generator 102, 220 may reduce average power levelsprovided during the energy cycle, for example, by reducing the current,voltage, duty cycle, or any other suitable property. In some examples,the generator 102, 220 may change the value of a threshold property,such as impedance, that indicates the end of the algorithm. For example,the threshold property may be modified in a manner that tends to reducethe total energy delivered during the energy cycle. In some examples,the generator 102, 220 may modify the energy cycle by applying one ormore maximum values. For example, the generator 102, 220 may apply amaximum total energy to be delivered during the energy cycle. If themaximum total energy is exceeded, then the generator 102, 220 mayterminate the energy cycle. That is, if the energy cycle has nototherwise terminated before the expiration of the maximum time, then thegenerator 102, 220 may terminate the energy cycle. Also, for example,where the energy cycle involves the application of a power curve,modifying the energy cycle may comprise reducing the power levelsdelivered over all or a portion of the power curve, for example, byapplying a multiplier. Where the energy cycle involves applying asegmented power curve, as described herein, modifying the energy cycleroutine may comprise, modifying the first and/or second power curves,reducing the ratio of first power curve segment widths to second powercurve segments widths, etc. Also, for example, the generator 120, 220may apply a maximum power, voltage, current, etc. The generator 120, 220may be programmed to prevent the power, voltage, current, etc., fromexceeding respective maximum values during the energy cycle.

FIG. 34 illustrates a flow chart showing another embodiment of a processflow 3200 for modifying a drive signal when a previous energy cycle hasalready been applied to a tissue bit. The process flow 3200 may beexecuted by a surgical system including any suitable type of surgicaldevice including, for example, the ultrasonic surgical device 104 andthe electrosurgical devices 106, 4106, 200 described herein. At 3202,the surgical system (e.g., a generator 102, 220 thereof) may receive anindication of jaw closure. When the surgical system uses an ultrasonicdevice, the indication of jaw closure may be an indication that theclamp arm 155 has been pivoted against the blade 151. When the surgicalsystem uses an electrosurgical device, the indication of jaw closure maybe an indication that the jaw members 167, 169 have been moved to aclosed position. The indication of jaw closure may come from anysuitable sensor or mechanism including, for example, proximity sensors191, 193, 195, 199, 4450, pressure sensors 156, 166, temperature sensors156, electrodes 157, 159, 177, 179, etc.

At 3204, the generator 102, 220 may receive an indication of an energycycle request, similar to 3102 described herein. At 3206, the generator102, 220 may provide a drive signal to the surgical device (e.g.,ultrasonic surgical device 104 or electrosurgical device 106, 4106, 200)according to the requested energy cycle. At 3208, the energy cycle maycease. For example, the energy cycle may terminate, at which point thegenerator 102, 220 may discontinue the drive signal. The generator 102,220 may then await a next request for an energy cycle. At 3210, thegenerator 102, 220 may receive a next request for an energy cycle, forexample, as described herein. At 3212, the generator 102, 220 maydetermine whether the jaws have opened since the provision of the firstenergy cycle (or, with the ultrasonic device 104, whether the clamp arm155 has pivoted away from the blade 151). If the jaws have opened, itmay indicate that the clinician has released the tissue bite treated bythe previous energy cycle. Accordingly, if the jaws have opened, thegenerator 102, 220 may, at 3206, provide the drive signal according tothe requested energy cycle. If the jaws have not opened, it may indicatethat the clinician intends to apply an energy cycle to the same tissuebite that was previously treated. Accordingly, at 3214, the generator102, 220 may provide a drive signal according to a modified energycycle, as described herein.

Although the various embodiments of the devices have been describedherein in connection with certain disclosed embodiments, manymodifications and variations to those embodiments may be implemented.For example, different types of end effectors may be employed. Also,where materials are disclosed for certain components, other materialsmay be used. The foregoing description and following claims are intendedto cover all such modification and variations.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

Various aspects of the subject matter described herein are set out inthe following numbered clauses:

1. A surgical system, the system comprising:

an end effector; and

a generator programmed to:

-   -   receive an indication of a first impedance of tissue to be        treated by the end effector;    -   determine that the first impedance is within an impedance range        corresponding to a first power curve segment of the segmented        power curve;    -   provide a drive signal to the end effector according to a first        power curve;    -   receive an indication of a second impedance of the tissue to be        treated by the end effector;    -   determine that the second impedance is within an impedance range        corresponding to a second power curve segment of the segmented        power curve;    -   provide the drive signal to the end effector according to a        second power curve.

2. The surgical system of clause 1, wherein the second power curve isless aggressive than the first power curve.

3. The surgical system of clause 1, wherein the second power curve has alower delivered power over a range of tissue impedance indicationsreceived by the generator, wherein the range of tissue impedanceindications comprises the indication of the first impedance and theindication of the second impedance.

4. The surgical system of clause 1, wherein the second power curve is aconstant power.

5. The surgical system of clause 4, wherein the second power curve is aconstant power between 0 Watts and 5 Watts.

6. The surgical system of clause 1, wherein a ratio of a width of thefirst power curve segment to a width of the second power curve segmentis between 1/10 and 10.

7. The surgical system of clause 6, wherein the ratio of a width of thefirst power curve segment to a width of the second power curve segmentis between ⅓ and 3.

8. The surgical system of clause 1, wherein the ratio of a width of thefirst power curve segment to a width of the second power curve segmentis about 1.

9. The surgical system of clause 1, further comprising a transducermechanically coupled to the end effector, providing the drive signal tothe end effector comprises providing the drive signal to the transducer.

10. The surgical system of clause 1, wherein the end effector furthercomprises a first electrode and a second electrode, and whereinproviding the drive signal to the end effector comprises providing thedrive signal to the first electrode and the second electrode.

11. The surgical system of clause 1, wherein the generator is furtherprogrammed to:

receive a request for an energy cycle routine to the end effector;

determine that the at least one jaw member has not been in the openposition since a conclusion of a previous energy cycle; and

apply a modified energy cycle routine to the end effector, whereinapplying the modified energy cycle routine delivers less energy thanapplying the energy cycle routine.

12. A surgical system, the system comprising:

an end effector; and

a generator to provide a drive signal to the end effector, wherein thegenerator is programmed to:

-   -   provide a drive signal to the end effector according to a first        power curve;    -   determine that an impedance of tissue treated by the end        effector has moved from an impedance range corresponding to a        first power curve segment to an impedance range corresponding to        a second power curve segment; and    -   provide the drive signal to the end effector according to the        second power curve.

13. The system of clause 12, wherein determining that an impedance ofthe tissue treated by the end effector has moved from an impedance rangecorresponding to a first power curve segment to an impedance rangecorresponding to a second power curve segment comprises:

receiving an indication of a first impedance of the tissue treated bythe end effector; and

evaluating a state transfer function based on the first impedance,wherein a result of the state transfer function indicates that the firstimpedance is within an impedance range corresponding to a second powercurve segment.

14. The system of clause 12, wherein determining that an impedance ofthe tissue treated by the end effector has moved from an impedance rangecorresponding to a first power curve segment to an impedance rangecorresponding to a second power curve segment comprises:

receiving an indication of a first impedance of the tissue treated bythe end effector; and

retrieving a drive signal characteristic corresponding to the firstimpedance, and wherein providing the drive signal to the end effectoraccording to the second power curve comprises applying the drive signalcharacteristic to the drive signal.

15. The surgical system of clause 12, wherein the second power curve isless aggressive than the first power curve.

16. The surgical system of clause 12, wherein the second power curve hasa lower delivered power over a range of tissue impedance indicationsreceived by the generator, wherein the range of tissue impedanceindications comprises the indication of the first impedance and theindication of the second impedance.

17. The surgical system of clause 12, wherein the second power curve isa constant power.

18. The surgical system of clause 17, wherein the second power curve isa constant power between 0 Watts and 5 Watts.

19. The surgical system of clause 12, wherein a ratio of a width of thefirst power curve segment to a width of the second power curve segmentis between 1/10 and 10.

20. The surgical system of clause 19, wherein the ratio of a width ofthe first power curve segment to a width of the second power curvesegment is between ⅓ and 3.

21. The surgical system of clause 12, wherein the ratio of a width ofthe first power curve segment to a width of the second power curvesegment is about 1.

22. The surgical system of clause 12, wherein the generator is furtherprogrammed to:

receive a request for an energy cycle routine to the end effector;

determine that the at least one jaw member has not been in the openposition since a conclusion of a previous energy cycle; and

apply a modified energy cycle routine to the end effector, whereinapplying the modified energy cycle routine delivers less energy thanapplying the energy cycle routine.

We claim:
 1. A surgical system, the surgical system comprising: an endeffector of a surgical instrument, wherein the end effector isconfigured to grasp tissue; a generator communicatively coupled to theend effector, the generator capable of delivering energy to the tissuegrasped by the end effector according to a first and second power curvestored in memory, wherein the first power curve defines a first range ofpower levels that is greater than a second range of power levels definedby the second power curve, wherein the generator is configured to:receive a tissue impedance value corresponding to an impedance of thetissue grasped by the end effector; and wherein when the tissueimpedance value is within a first range of tissue impedance, thegenerator is further configured to: deliver energy to the end effectoraccording to the first power curve; and wherein when the tissueimpedance value is within a second range of tissue impedance, thegenerator is further configured to alternately apply segments of thefirst and second power curve to reduce a rate of increase of tissueimpedance within the second range of tissue impedance by: generating asegment of the second power curve to deliver energy to the end effectoraccording to the segment of the second power curve while the tissueimpedance value is within a first subrange of the second range of tissueimpedance; and generating a segment of the first power curve to deliverenergy to the end effector according to the segment of the first powercurve while the tissue impedance value is within a second subrange ofthe second range of tissue impedance.
 2. The surgical system of claim 1,wherein the generator is further configured to alternate between energyto be delivered to the end effector according to the segment of thesecond power curve and energy to be delivered to the end effectoraccording to the segment of the first power curve.
 3. The surgicalsystem of claim 1, wherein the energy to be delivered to the endeffector according to the segment of the second power curve is less thanthe energy to be delivered to the end effector according to the segmentof the first power curve.
 4. The surgical system of claim 1, wherein atotal energy to be delivered to the end effector according to the secondpower curve is less than a total energy to be delivered to the endeffector according to the first power curve.
 5. The surgical system ofclaim 1, wherein the second power curve defines a constant power.
 6. Thesurgical system of claim 5, wherein the second power curve defines aconstant power between 0 Watts and 5 Watts.
 7. The surgical system ofclaim 1, wherein a ratio of a width of the segment of the first powercurve to a width of the segment of the second power curve is between1/10 and 10, wherein the width defines a difference between a minimumvalue and a maximum value of a subrange.
 8. The surgical system of claim1, wherein a ratio of a width of the segment of the first power curve toa width of the segment of the second power curves between ⅓ and 3,wherein the width defines a difference between a minimum value and amaximum value of a subrange.
 9. The surgical system of claim 1, whereina ratio of a width of the segment of the first power curve to a width ofthe segment of the second power curve is about 1, wherein the widthdefines a difference between a minimum value and a maximum value of asubrange.
 10. The surgical system of claim 1, wherein the generator isfurther configured to: receive a request for an energy cycle routine tobe delivered to the end effector; determine that at least one jaw memberof the end effector has not been in an open position since a conclusionof a previous energy cycle; and deliver a modified energy cycle routineto the end effector, wherein delivering the modified energy cycleroutine delivers less energy than delivering the energy cycle routine.